Maybe it is. Maybe none of it is true and it's just been put in their heads to stop them wanting to go home. Maybe even the possibility it's true is enough.
Jack, certainly, is in no hurry to go home and find out if that was it, he never did wake up from bleeding out into the Miracle.
But that's negative thinking and he's doing his best to focus on the positive here. His lips twitch at Spike's comment, and his eyes are warm. "Good thing we've got some really good things here to make the most of." And that incluedes moments like this with you, Spike.